This invention relates to an apparatus and method for recovering oil from an oil bearing soil by means of the generation of a shock wave in a liquid in the bearing soil.
As used in this specification, the term "oil" means natural oil or petroleum as found in nature particularly in oil bearing soils. Such a product is often called "crude oil" which consists principally of hydrocarbons.
The removal of oil by the use of drilled oil wells in the oil bearing soil has been practiced for several generations. Many of the wells have ceased to be utilized because it is not economical to remove the oil which remains in the soil by conventional methods. To remove the oil which is left behind in a reservoir, such oil being called "residual oil", it has been suggested to use various techniques. The primary technique is to flood the well with water in order to induce further flow. In addition to water flooding, other techniques have been developed such as the injection of liquified petroleum gas, solvents, or surfactants into the well, usually before the water flooding occurs.
In addition, it has been suggested to use a thermal explosion at the bottom of the well, hopefully to cause additional fissures in the oil bearing soil so as to increase the oil flow. Obviously, thermal explosions have the disadvantage of destroying the well and, also, of having a limited effect if they are to be kept from destroying the well.
Accordingly, it is an object of the present invention to provide a method and apparatus for recovering oil from an oil bearing soil by increasing the oil flow with a minimum of damage to the oil well.
It is a further object of the present invention to provide a method and apparatus which can be easily and efficiently placed in the well with a minimum of shut down time of well operations.
It is another object of the present invention to provide recovery method which is economical in operation as well as requiring a minimum amount of fixed equipment.